1. Field of the Invention
Embodiments of the present invention relate to a communication technology using multiple antennas, and more particularly, to an arrangement of the multiple antennas in a channel where a Line-Of-Sight signal and a reflection signal are mainly provided.
2. Description of the Related Art
Multiple antennas may be mainly used in a wireless and mobile communication field. When using the multiple antennas, a plurality of transmission paths that are spatially separated from each other while using the same time and the same frequency, may be created. Accordingly, in a case of using the multiple antennas, a capacity of a transmittable signal may advantageously increase even using the same power.
Multi-path signals as signals used in a wireless Local Area Network (LAN) or a mobile communication may be reflected and/or scattered by an object while being transmitted. In this case, after being scattered, a signal may have a random phase unrelated to a phase of an input signal. In this regard, an environment where a large number of objects causing the signals to be scattered exist around a transmitter and a receiver may be referred to as a rich-scattering environment, and the rich-scattering environment may be an important condition for enabling a multi-antenna communication technology to have a high performance. As another condition for the high performance of the multi-antenna communication technology, a distance between each antenna in a multiple antennas respectively positioned in the transmitter and the receiver may need to be one half a wavelength of a transmitted signal. However, in the rich-scattering environment, a direction of the multiple antennas of the transmitter and the receiver may not affect a performance of the multiple-antenna communication technology.
All wireless channels may not have the rich-scattering environment. When a frequency of a signal significantly increases, that is, when a wavelength of a signal decreases, the signal may be less easily scattered. So that the signal is scattered, a size of an object may need to be significantly reduced to be less than the wavelength of the signal, otherwise when the wavelength of the signal is significantly reduced to be less than the size of the object, the object may only reflect the signal without scattering the signal.
In a case of a channel where a signal-scattering phenomenon does not occur, having the distance between the multiple antennas corresponding to one half the wavelength of the transmitted signal may not ensure the high performance of the multi-antenna communication technology. Also, the direction of each multiple antenna arrangement, which may affect the performance of the multiple-antenna communication technology, may be a significant problem.
Accordingly, in a case of the channel where the signal-scattering phenomenon does not occur, there is a desire for a method to determine the distance between each antenna in a multiple antennas that may ensure the high performance of the multi-antenna communication technology and a method to determine the direction of each arrangement of the multiple antennas affecting the high performance.